劳动法规定，劳动者解除劳动合同应提前（）天以（）形式通知用人单位。
A．15/书面
B．15/口头
C．30/书面
D．30/口头
参考答案：C
Next, John Snow ______ the source of the water for these two streets and found it came
from the polluted river.
A. looked into
B. looked up
C. looked after
D. looked around
